This invention relates to a rope and a method for forming the same and, more particularly, to a rope and a method thereof in which reinforcing fibers having high tensile strength and low elongation, such as glass fibers or aramid fibers, are used.
For a rope having high tensile strength and low elongation, a wire rope has been widely used in which a number of steel wires are layed, braided or plaited with each other or are so formed around a fiber core such as jute yarns so as to have desired rope structures and diameters in accordance with various usages.
Due to this high tensile strength and low elongation, the wire rope has an advantage over natural fiber ropes made of Manila hemp or sisal hemp and known synthetic fiber ropes made of nylon or polypropylene. Onn the other hand, compared with the fiber ropes, many disadvantages have been experienced in the wire rope owing to its heavy weight, electrical conductivity, and corrosiveness. Accordingly, when a wire rope having the length of hundreds or thousands of meters is used, vast supporting devices, suspension devices or winding devices must be used due to the heavy weight of the wire rope, so that there is a limit in the use of such a wire rope in some instances, such as dredging the bottom of the ocean or such. Furthermore, due to the electrical conductibility of the wire, when the wire rope is to be used as a stay for an antenna or such, insulators must be used to connect the rope with the wires, thereby causing complexity of the structure. The corrosiveness of the wire rope will weaken the tensile strength thereof and further cause trouble in the operation of the winder of the rope or such.
In known fiber ropes, fibers or fiber bundles are twisted and then layed, braided or plaited as referred to hereinafter as "formed into a rope structure" so as to maintain the desired configuration of the fiber rope. However, it is known that such twisting and forming of the fibers into a rope structure remarkably reduces the tensile strength of the fiber itself so tht most of the fiber rope thus formed has a tensile strength of less than 50 percent of that of the fiber bundles gathered without twisting. Accordingly, when fibers such as nylone or polypropylene having relatively high elongation compared with the steel wire are used for the fiber rope, the elongation of the fiber rope will be much increased due to the twisting and forming steps of the rope structure and will become several to tens of times of that of the wire rope. Thus, this fiber roping cannot be used as suspension ropes or supporting ropes for heavy loads. Further, the fiber ropes are generally weak against abrasion and therefor, the fiber ropes will easily be injured or damaged wwhen they movably contact or slide against any rough surface and can be cut by sharp, knife-like edges.
Accordingly, an object of the present invenion is to provide a rope which eliminates the disadvantages of the wire rope and the known fiber ropes set forth above.
Another object of the present invention is to provide a rope light in weight which has high tensile strength and low elongation.
A further object of the present invention is to provide a relatively flexible rope light in weight which may be advantageously used in a dynamic condition with a winder or such.
A further object of the present invention is to provide a relatively flexible rope light in weight which can absorb high external force applied in the radial direction thereto at a place where the rope contacts a wind-up drum or such.
Still another object of the present invention is to provide a method for forming a rope having the above defined characteristics.